Embodiments disclosed herein relate to an aircraft tail rotor system, and more particularly, to a pitch change shaft bearing assembly for use with an aircraft tail rotor system.
In a typical rotary wing aircraft, such as a helicopter for example, a tail rotor system converts tail driveshaft rotary power into the aerodynamic forces necessary to control the direction of flight and to counteract main rotor torque.
A tail rotor head system provides a mounting point for connecting a plurality of tail rotor blades to a blade pitch change mechanism. The pitch of the tail rotor blades is controlled by a position of a tail rotor pitch change shaft. The position of the pitch change shaft is controlled by a pitch change servo. When the pitch change servo pulls the pitch change shaft inboard, the pitch beam and the pitch change links twist the tail rotor blades about internal elastomeric bearings to increase the blade pitch. Conversely, when the pitch change servo permits the pitch change shaft to move outboard, the pitch change shaft bearing and the pitch change links twist the tail rotor blades about internal elastomeric bearings to decrease blade pitch. This adjustment in the blade pitch is used to control a turning direction of the aircraft.
The pitch change shaft rotates with and moves linearly within a rotating tail rotor shaft, also commonly referred to as an output gear shaft. A pitch change bearing supports the pitch change shaft within the tail rotor shaft and allows the pitch change shaft and tail rotor shaft to rotate independently of the non-rotating pitch change servo rod. In a typical arrangement, the pitch change shaft bearing outer raceway rotates with the pitch change shaft and the tail rotor shaft, while the inner raceway is non-rotating hut moves linearly with the pitch change servo rod.